Typical edge-lit LCD devices in mass production needs to employ a light guide panel (LGP). Because the light coupling distance between a light source of a backlight module and the LGP is required to be accurate, the LGP tends to be rigidly positioned. However, the light emitting diode (LED) lightbar of the LCD device radiates heat while in use, which heats and expands the LGP made of high polymer material such as polymethyl methacrylate (PMMA), poly carbonate (PC) and the like. Because a positioning structure has no buffer performance, the following problems may come: the heat expansion or cold contraction quantity of the LGP cannot be fully absorbed, easily causing the warpage and deformation of the LGP. Additionally, the LGP is in rigid contact with the positioning structure, easily causing the LGP to be fractured when being impacted.
To solve the aforementioned problems, as shown in FIG. 1, an LGP 2 is arranged in a backplane 1, and a part of an LCD device is specially reserved with an expansion clearance for the LGP 2. Thus, a long light coupling distance is generated between an LED lightbar 3 and the LGP 2, and light incident efficiency is reduced.